In recent years, as disclosed in Patent Document 1, technology utilizing a magnetic field resonance mode has been proposed as technology for wirelessly supplying electric power instead of utilizing electromagnetic induction or radio waves. According to such wireless power supply technology that uses a magnetic field resonance mode, for example, a resonator having a resonant angular frequency of ω1 is provided in a power transmitting device, and a resonator having a resonant angular frequency of ω2 is provided in a power receiving device. A resonant circuit that connects a coil and a capacitor is applied as a resonator. By tuning the resonant angular frequencies ω1 and ω2 and appropriately adjusting the size and arrangement of the resonators, a magnetic field resonance mode is generated in which energy can be transferred between the power transmitting device and the power receiving device, and power is wirelessly transmitted from the resonator of the power transmitting device to the resonator of the power receiving device. According to this wireless power supply technology, the power utilization efficiency (energy transfer efficiency) may be several tens of percent, so that a distance between the devices can be relatively large, and the power receiving device can be separated by several tens of centimeters or more from the power transmitting device.    Patent Document 1: Japanese National Publication of International Patent Application No. 2009-501510